1. Field of the Invention
The invention relates satellite navigation systems and more particularly improved methods for determining azimuths using Global Positioning System (GPS) satellites.
2. Description of the Prior Art
The prior art methods to determine astronomic azimuth generally use a theodolite and precision clock. Astronomic azimuth is azimuth calculated at a refernce site in the natural coordinates. Angles to a reference star and to a target location are measured and time marked. Based on knowing star location and angles at these time marks, and taking the spin of the earth into account, an estimate of astronomic azimuth is made using data collected over, generally, a several hour time period.
The prior art procedures require precision theodolites. This equipment is very expensive and sensitive to mechanical damage. Additionally, clear weather is required in order to sight stars. The conventional method is limited in accuracy. Depending on equipment, accuracy is usually not better than one arcsecond.